Hello there @Cerveraa !
Checking around the community, this type of issue has popped around from time to time. Since you already updated your drivers, the next step for that would be to do a clean install, and replace the regular drivers for Developers ones.
The next usual suspect, are graphical overlas. If you have any of those active (nVidia, Xbox, Discord, etc), disable them, and check if the flickering stops in UE. Finally, just for testing, disable one of your monitors, just to ensure this has nothing to do with the multi-monitor setup.